Stop joint for oil-filled cables



March 2, 1937. L. EMANUEL! 2,072,742

STOP JOINT FOR OIL-FILLED CABLES Filed Nov. 2, 1935 E LIQUID Fi 5FACTORY 1 i FILLED O a O by 6A9 His .Attorn ey.

Patented Mar. 2, 1937 UNITED STATES STOP JOINT FOR OIL-FILLED CABLESLuigi Emanueli, Milan, Italy, assignor to Societa Italiana Pirelli, acorporation of Italy Application November 2, 1935, Serial No. 48,006 InItaly January 30, 1935 5 Claims.

The present invention is directed to an improvement in stop joints foroil-filled cables of the character disclosed in my Patent No. 1,979,149,issued October 30, 1934, and has for its object an 5 improvedarrangement of parts whereby the interior parts of the joint may be moreeffectively evacuated and filled with degasified oil.

According to my present invention, a means is provided to obtain a morecomplete impreg- 10 nation of the fibrous insulating parts, generallymade up of insulating paper which is wound under tension around theinside metal-parts of the joint. In this way a higher dielectricstrength of the insulating parts themselves is obtained,

15 and the joint is therefore capable of resisting higher workingtensions.

One form of execution of the present invention, as an example, isdescribed hereunder and is illustrated in the attached drawings, inwhich:

Fig. 1 is a longitudinal section of one-half of the joint body, that is,of the part of the joint prepared in the factory;

Fig. 2 is a side view of the end of one of the two cables to be joined,ready to be introduced in 25 the joint body;

Fig. 3 shows, on an enlarged scale, in longitudinal section, aparticular valve appertaining to the joint body;

Fig. 4 shows on an enlarged scale, a section 30 taken on line A-A of apart of Fig. 3;

Fig. 5 shows the side view of a tool for closing said valve after thejoint body has been impregnated, and

Fig. 6 is a sectional view of a closure which is 35 temporarily appliedto the joint body during impregnation.

All the parts of the stop joint of the present in vention, except thoseshown in Figs. 3 and 5 may be constituted in the same way as the stopjoint 40 described in my aforesaid patent.

The joint body, one-half of which is represented in Fig. 1, is formed bythe outside casing l' to which supports 2 for the insulating tubes 3 arefixed, the latter carrying contact sockets or 45 caps 4 which areelectrically connected together by flexible couplings 5. A metallicscreen 6, provided with holes or perforations l, is connected to thesockets or caps 4 by a wire 8, said screen defining a central chamber llcontaining liquid in- 50 sulation. Insulating coverings 9 of fibrous material, generally paper, impregnated with oil or other insulatingliquid, cover the screen and part of the insulatingtubes, thus formingan obstacle of considerable dielectric strength against the 55 dischargebetween said screen, which is at the potential of the cable conductor,and the outside casing which is connected to its lead sheath and toground. The space or chamber l inside the joint body defined by theinsulation 9 and the casing wall, including the space or cl-;.mber llinside the screen 6, is completely filled with degasified oil or otherinsulating liquid in the factory. The other half of the joint body beingthe same as that illustrated, further illustration and description areunnecessary. 10

The ends of the two cables to be joined are prepared in a known manner,as shown in Fig. 2, in which can be seem-the connector I! with itsspring pressed contact members, the insulating wrapping l3 which coversthe cable, the electrostatic control M, the lead sheath [5 of the cableand, soldered to it, one of the end parts l6 of the outside casing ofthe joint. The end of each of the two cables is introduced into thejoint body, so that the connector l2 forms a good contact with the cap4. After this the casing l of the joint is soldered to the end parts I6. The free spaces inside of the insulating tube 3 around the conductorends is then filled with oil, the opening l8 and connected pipe beingused for the 5 purpose.

For filling the joint body and for the contemporaneous impregnation ofthe insulating covering 9, which operations are carried out in thefactory, in the stop joints so far known vacuum was first made throughoneor two holes existing in the outside casing, such as that indicatedwith IS, and the oil was forced in afterwards. This procedure, however,did not result in as perfect an impregnation as is desirable for theinsulating covering 9, especially the inside layers which are in contactwith the screen 6 under tension. One of the difliculties met with wasthat of removing the air from the space it through the holes I of thescreen and through the great thickness and 40 large area of the covering9. g

This difiiculty has been overcome by the present construction, accordingto which the evacuation and the filling with oil are made, not onlythrough the opening I9 and connected pipe of the outside casing but alsothrough the port 20 at the bottom of one of the caps 4, as shown on anenlarged scale in Fig. 3. The port 20 can be closed by a conical valve2| provided with a prolongation 22, the section A--A of which is shownin Fig. 4. A flexible steel wire 23, kept in position oy the support 24,passes transversely through said prolongation. When the wire is inresting or neutral position, the port 20 is open. To close the port itis necessary to press the valve to its seat by bending the wire, thisbeing done by screwing a piece or plug 25 into the base of the cap 4.This can be held and operated by slipping the squared end 21 of the toolshown in Fig. into the square opening 26. Fig. 1 shows the valve closedwhich is its normal position.

In order to fill and impregnate the joint body I in the factory, the endof the casing on the side of the contact cap having the valve 2| isfirst of all closed by soldering a cover 28, Fig. 6, to said end, thecover being provided with an opening 29 and connected pipe. From thisopening and from theopening IS the air contained in the casin bothinside and outside of the insulation 9 is pumped until the best possiblevacuum is obtained, then through these same openings oil fiows, thatwhich enters through the opening 29 first fills the space H and thenfiows through the port 20 and fills the central space H, andsubsequently passes therefrom through the holes 1 of the screen andimpregnates the insulation 9. At the same time, other oil flowingthrough the opening l9, cooperates in this impregnation.-

As a result, the whole'joint body is filled with oil. In this way theinsulating coverings 9, whose inside layers are in contact with thescreen H are the first to be reached by the oil, and are therebyperfectly impregnated. By subjecting both sides of the insulation 9 tovacuum at the same time, the removal of gases therefrom is greatlyfacilitated. By supplying impregnating liquid to both sides of theinsulation at the same time, the period of time required for theoperation is decreased and better results obtained.

The high dielectric strength so given to the insulation renders thejoint capable of withstanding very high working tensions.

When the whole of the joint body has been filled with oil, an oilreservoir 30 under pressure is applied to the opening l9 through theconnected pipe, then the cover 28 shown in Fig. 6 is unsoldered andremoved from thejoint casing. Lastly, the screw threaded plug 25 isslipped on the end 21 of the tool shown in-Fig. 5 and is screwed to thebase of the cap 4, so closing, with the conical valve 2|, the port 20.While screwing the plug 25 into place the joint casing should standvertically so that the column of oil in the chamber I'I preventsentrance of air and escap of oil from the chamber ll.

The joint body is then ready to be dispatched to the place of laying,the small oil reservoir 30 under pressure connected to theopening I!)being left still attached thereto.

What I claim as new and desire to secure by Q Letters Patent of theUnited States, is:-

p 1. A stop joint for cables filled with liquid insulation comprising acasing, a pair of insulating tubes supported thereby and arranged toreceive cable ends, sockets supported by the adjacent ends of the tubesfor receiving the cable ends and electrically connecting them, aperforated metallic screen supported by the tubes and surrounding thesockets, said screen defining an internal chamber, liquid impregnatedinsulation covering the screen, and means establishing a directcommunication from the chamber through one of the sockets to the outsideof the casing for evacuating the chamber and subsequently filling itwith liquid to impregnate the insulation.

2. A stop joint for cables filled with liquid insulation comprising acasing, apair of insulating tubes supported thereby and arranged toreceive cable ends, sockets supported by the adjacent ends of the tubesfor receiving the cable ends and electrically connecting them, a portand an open valve in one of the sockets, a perforated metallic screensupported at its ends by the tubes and surrounding the sockets, saidscreen defining a central chamber, a wrapping of liquid impregnatedinsulation surrounding the screen, means for establishing a directcommunication from the chamber through the port to the outside of thecasing to permit evacuation of the chamber and subsequent filling of itand impregnation of the insulation with liquid, and a means carried bythe socket having the valve for permanently closing it.

3. As an article of manufacture, a body for a stop joint comprising acasing, an insulator having open ends, a contact receiving socketsupported by one end of the \insulator, a port and valve in the socket,means for holding the valve open, a perforated screen supported at oneend by the insulator and defining a central chamber, a wrapping offibrous insulation around the screen, the wrapping and easing definingan outer chamber between them, a cap for temporarily closing one end ofthe casing, and conduit means connected to the casing and cap throughwhich the fibrous insulation may be evacuated and subsequently filledwith liquid insulation from both sides thereof.

4. The method of treating the body of a stop joint having a casing, acentral and an outside chamber within the casing, a body of perviousinsulation forming a well between the chambers, sockets for theconductor ends, and a valve controlled port in one of the socketsthrough which communication may be established between the centralchamber and the outside of the casing, which comprises establishingcommunication between both chambers and the outside of the casing,simultaneously evacuating the chambers and the wall of insulation, thenfilling the chambers with liquid to impregnate the insulation from bothsides thereof, and subsequently closing the communication between theoutside chamber and the outside of the casing and sealing the portcommunicating with the inside chamber.

5. The method of treating the body of a stop joint having a casing, acentral and an outside chamber within the casing, a body of fibrousinsulation forming a wall between the chambers, and a ported socket fora conductor end, which comprises temporarily capping an end of thecasing, establishing one connection through the CERTIFICATE OFCORRECTION- latent No. 2.072.742. March 2. 1937.

LUIGI EMANUELI.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,second column, line 39, claim 4, for the word well" read wall; and thatthe said Letters Patent should be read with this correction therein thatthe same may conform to the record of the case in the Patent Office.

Signed and sealed this 30th day of March, A. D. 1937.

Henry Van Arsdale (Seal) Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION.

Patent No. 2.072.742. I March 2. 1937.

tum: EMANUELI.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,!second column, line 39, claim 4, for the word "well" read wall; and thatthe said Letters Patent should be read with this correction therein thatthe same may conform to the record of the case in the Patent Office.

Signed and sealed this 30th day of March, A. D. 1937.

Henry Van Arsdale (Seal) Acting Commissioner of Patents.

